Breast cancer screening

On the 20 and 21 December 2008, a number of newspapers reported that the first baby to be screened to avoid hereditary breast cancer is due to be born.

While most of the reporting was accurate, several newspapers published misleading information.

What actually happened?

Doctors at University College Hospital, created a number of embryos through in vitro fertilisation for a couple whose future children were at very high risk of inheriting the BRCA1 breast cancer causing gene. These embryos were screened to select an embryo free from a mutated version of the BRCA1 gene that could lead to the resulting person developing breast cancer.

The embryo which was chosen was not genetically manipulated or programmed. The cancer causing gene was not removed from the embryo.

Using preimplantation genetic diagnosis (PGD), a cell is removed from the embryo and tested. An embryo without the BRCA1 gene was then implanted in the mother’s womb. All uses of PGD screening are licensed by the HFEA.

More about preimlantation genetic diagnosis

Preimplantation genetic diagnosis (PGD) involves genetically testing an embryo in a laboratory. To achieve this, couples have in vitro fertilisation (IVF) treatment followed by an additional genetic testing stage.

The embryo is grown in the laboratory for a couple of days until the cells have divided and the embryo consists of eight cells. At this time a specially trained embryologist will remove one or two of the cells.

The cells can then be tested to see if the embryo from which they were removed contains the faulty gene that causes the condition in the family. One or two of the embryos without a copy of the faulty gene can be placed into the woman in the hope that they will develop.

Any remaining unaffected embryos can be stored for later use as required. Those embryos that had a copy of the faulty gene are not used.